Conventional drums have a cylindrical body or shell with an upwardly directed flat circumferential end surface upon which a drum head of flat circular configuration is mounted. A ring shaped rim is fitted over the outer circumference of the head, the cooperating surfaces of the shell and head being such that depressing the rim downwardly tends to increase the lateral tension within the head.
A number of tensioning rods, typically about eight, are located in circumferentially spaced relationship about the periphery of the drum body or shell. The tensioning rods have their upper ends rotatably supported by the rim and extend downward about the outer wall of the cylindrical body. The lower ends of the tensioning rods are threaded, and are received in threaded securement devices which in turn are secured to the drum body so that when the tensioning rods are driven in rotation from their upper ends that will shorten them and hence tighten the drum head.
Achieving optimum adjustment of tensioning rods and associated securement devices is sometimes very difficult or inconvenient. It is desirable for the drum head to be correctly centered upon the upper end surface of the shell or body and with a uniform lateral tension throughout. The securement devices sometimes need to be replaced because of wear.
The drum head, like other musical instruments, has a basic frequency of vibration together with associated overtones at higher frequencies, to produce a characteristic musical tone. Another problem with drums is that the primary sounds generated by vibration of the drum head are sometimes accompanied by noise which is created separately by rattling of the securing devices, and is not usually compatible with the desired overall tone pattern. These noises may be referred to as side effect sounds—that is, sounds that are not desired and may be annoying to a listener.